G. Marconi, an Italian inventor, unlocks the path of
recent day wireless communications by communicating the
letter ‘S’ along a distance of 3Km in the form of three dot
Morse code with the help of electromagnetic waves. After
this inception, wireless communications have become an
important part of present day society. Since satellite com-
munication, television and radio transmission has advanced
to pervasive mobile telephone, wireless communications has
transformed the style in which society runs. The evolution
of wireless begins here [2] and is shown in Fig. 1. It shows
the evolving generations of wireless technologies in terms of
data rate, mobility, coverage and spectral efficiency. As the
wireless technologies are growing, the data rate, mobility,
coverage and spectral efficiency increases. It also shows
that the 1G and 2G technologies use circuit switching while
2.5G and 3G uses both circuit and packet switching and
the next generations from 3.5G to now i.e. 5G are using
packet switching. Along with these factors, it also differ-
entiate between licensed spectrum and unlicensed spectrum.
All the evolving generations use the licensed spectrum while
the WiFi, Bluetooth and WiMAX are using the unlicensed
spectrum. An overview about the evolving wireless
technologies is below: